This application is based on and incorporates herein by reference Japanese Patent Application No. 2001-242811 filed on Aug. 9, 2001.
1. Field of the Invention
The present invention relates to a wiper control system for automatically wiping off raindrops landed on a window glass of an automotive vehicle, a ship, an airplane or the like, and particularly to a wiper control system for sensing an amount of raindrops with a raindrop sensor and controlling the operation of wipers based on the measured amount of raindrops.
2. Description of Related Art
One type of such a wiper control system of a vehicle optically measures an amount of raindrops landed on a window glass during each wiping period of wipers with a raindrop sensor. Then, the wiper control system controls a wiping speed or movement of the wipers based on the measured amount of raindrops.
In such a wiper control system, even if an actual rainfall does not change substantially from one wiping period to the next wiping period, the amount of raindrops measured with the raindrop sensor may substantially change from one wiping period to the next wiping period due to, for example, a change in a direction of wind applied to the window glass of the running vehicle. The substantial change in the measured amount of raindrops from one wiping period to the next wiping period normally results in a change or fluctuation in the wiping speed of the wipers from one wiping period to the next wiping period, which is annoying to occupants of the vehicle.
The present invention addresses the above disadvantage. Thus, it is an objective of the present invention to provide a wiper control system, which can conduct more stable wiping operation of a wiper(s) in correspondence with an amount of raindrops landed on a window glass. It is another objective of the present invention to provide a method for controlling a wiper(s) in more stable manner in correspondence with an amount of raindrops landed on a window glass.
To achieve the objectives of the present invention, there is provided a wiper control system including a wiper for wiping off raindrops landed on a window glass, a sensing means for taking a measurement of an amount of raindrops present in a predetermined area of the window glass at a predetermined time in each wiping period of the wiper, an average amount calculating means for calculating an average amount of raindrops in each wiping period of the wiper by averaging a predetermined number of the latest measurements measured with the sensing means, and a wiper control means for controlling operation of the wiper based on the average amount of raindrops, which is calculated by the average amount calculating means. The sensing means is disposed in a wiping range of the wiper on the window glass.
To achieve the objectives of the present invention, there is also provided a method for controlling a wiper, which wipes off raindrops landed on a window glass. According to the method, a measurement of an amount of raindrops present in a predetermined area of the window glass is taken at a predetermined time in each wiping period of the wiper. Then, an average amount of raindrops is calculated in each wiping period of the wiper by averaging a predetermined number of the latest measurements. Thereafter, operation of the wiper is controlled based on the average amount of raindrops.